Systems for improving the efficiency of heating plants have been known in which combustion gases from one plant are passed downwardly through the top of the diverter box and then upwardly through the top of the box to the chimney, the bottom of the box being open so that the pressure of the surrounding air establishes a head which provides a heat lock so as to restrict air passage downwardly into the box, thus causing more heat to be absorbed in the plant and less to be passed out to the chimney.
Such a system is described in U.S. Pat. No. 4,009,705. A difficulty which has been experienced in the use of such known systems of this type is that, as a practical matter, their use has been limited to but a single heating plant. When more than one heating plant is connected to the diverter box of systems heretofore known, the inevitable result has been to blow out the pilot flame in one or another of the plants. This result has rendered impractical the use of such prior devices for handling gases from more than one plant.
This disadvantage affects the economic value of the diverter device where, as is common, two heating units, such as a furnace and a water heater, must be served.
Accordingly, it is an important object of the present invention to provide a system in which more than one heating unit may be served using a single diverter box but without unwanted consequences such as a blowing out of the pilot in any one of the multiple plants being served.